1. Field of the Invention
The present invention pertains to freezers that transport food products on a conveyor belt inside the freezer, and more particularly, to freezers that use fluidized beds that simultaneously freeze and transport the product.
2. Description of the Related Art
Fruits and vegetables are commonly process in large industrial freezers with conveyor belts that carry the product through various freezing zones inside the freezer. Ideally, when the fruit or vegetable products travel through the freezer and reach the end of the conveyor belt, the individually pieces of fruit or vegetable products are frozen with little or no damage.
Some fruits, such as raspberries, blackberries, and marionberries, are soft when ripe, can be easily squished or destroyed when processing. The berries are made up of small pieces, called drupelets that easily detached from the berry when handled reducing the berry's size.
In the prior art, freezer conveyor belts have been used to process raspberries, blackberries and marionberries. Typically, the location where the berries enter the conveyor belt, commonly known at the ‘wet zone’, is where the berries are soft, stick together, and most susceptible to damage. While in the wet zone, the berries are submerged in a liquid nitrogen bath which ‘crust freezes’ the berries. After leaving the liquid nitrogen bath, the berries are then deposited onto a fluidized bed conveyor belt where they undergo further freezing.
The cost of liquid nitrogen is very expensive. Also, on a fluidized bed conveyor belt, the velocity of the cold air delivered directly into the belt is often irregular creating violent ‘blowout holes’ in the fluidized layer of berries that damage to the berries. Sometimes, the ‘blowout holes’ are relatively large and interfere with the fluidizing process.
What is needed is an improved freezer conveyor belt system that is more efficient in cooling product transported on a fluidizing bed conveyor belt that does not require using liquid nitrogen, and reduces the occurrence of ‘blowout holes’ in the fluidized bed.